Polar environments can be among the simplest environments on Earth, making them excellent models to understand ecosystem processes and the responses of microorganisms to environmental perturbations. This vulnerability and the rate of the ongoing change make polar environments a priority in climate change and bioremediation studies. This chapter covers studies based on large-scale 16S rRNA gene libraries, environmental microarrays, large-insert clone libraries, and shotgun genome sequencing that are applying metagenomic techniques to characterize and understand polar ecosystems. A recent study at sites ranging from the Falkland Islands all the way to the base of the Antarctic Peninsula used 454 GS FLX Titanium sequencing of the 16S rRNA gene to compare the bacterial community structure and diversity in warmed versus control plots. This study revealed that soil warming induced significant shifts in the major soil bacterial groups like Acidobacteria and α-Proteobacteria, which led to changes in soil respiration. A recent shotgun metagenomic study in the Canadian High Arctic sequenced a permafrost sample and its overlying active-layer soil and focused particularly on genes that might be important for greenhouse gas emissions following permafrost thaw. The only metagenomic study of polar freshwater ecosystems published to date looked at the viral communities of an Antarctic lake. This study revealed that a large proportion of the viral sequences retrieved from the lake were from eukaryotic viruses and not from bacteriophages. Emerging technologies could also be interesting to apply to polar environments. For instance, bioremediation studies could benefit from metabolomics, proteomics, and newly developed reactome arrays.

23. IPCC. 2007. Climate Change 2007: the Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, United Kingdom and New York, NY.